1. Field of the Invention
The present invention generally relates to a wireless communication terminal, a transmission control method, and a computer program. More specifically, the present invention relates to a wireless communication terminal that is suitable for suppressing heat generation caused by a transmission power for wireless communication.
Priority is claimed on Japanese Patent Application No. 2005-283877, filed Sep. 29, 2005, the content of which is incorporated herein by reference.
2. Description of the Related Art
All patents, patent applications, patent publications, scientific articles, and the like, which will hereinafter be cited or identified in the present application, will hereby be incorporated by reference in their entirety in order to describe more fully the state of the art to which the present invention pertains.
A card-type wireless communication terminal has been known. The card-type wireless communication terminal can be configured to be inserted into a card slot of a PC (Personal Computer). Some models of the card-type wireless communication terminal cause a large amount of heat generation in transmission operation. The card slot of PC allows the generated heat to reside therein, thereby increasing a temperature of the wireless communication terminal. The temperature increase of the wireless communication terminal can provide an influence to devices integrated in the wireless communication terminal, thereby shortening a life-time of the wireless communication terminal.
One of the issues to be solved in connection with the wireless communication terminal is how to realize an efficient heat radiation from he card slot. Another issues is how to suppress the heat generation. The card slot is configured to allow accumulation of the generated heat therein. Some conventional techniques for suppressing the heat generation of the wireless communication terminal have been proposed.
Japanese Unexamined Patent Application, First Publication, No. 2003-309473 discloses a first conventional technique for suppressing heat generation in the wireless communication terminal. FIG. 23 is a block diagram illustrating a typical example of the conventional inter configuration of the wireless communication terminal. FIG. 24 is a diagram illustrating examples of variations of temperature and transmission power of the conventional wireless communication terminal. A timer is started to count during a continuous transmission with the normal power. When the counted value reaches a predetermined value, the transmission power is attenuated, while continuing the transmission and monitoring a temperature sensor. When the temperature becomes higher than the threshold as upper limit of a predetermined allowable temperature range, the transmission power supply is terminated to suppress any further heat generation.
The first conventional technique allows a temperature rising over the threshold as upper limit of the allowable temperature range while continuing the transmission with the normal power.
Japanese Unexamined Patent Application, First Publication, No. 2002-271124 discloses a second conventional technique for suppressing heat generation in the wireless communication terminal. FIG. 25 is a diagram illustrating examples of variations of temperature and transmission power of the conventional wireless communication terminal. When the temperature becomes higher than the threshold as upper limit of a predetermined allowable temperature range, the transmission power is reduced to decrease the temperature. When the temperature becomes lower than the threshold as upper limit of the predetermined allowable temperature range, the transmission power is increased to recovery of the original transmission power.
The second conventional technique suppresses the transmission power once after the temperature has risen over the threshold as upper limit of the allowable temperature range. Namely, it is difficult for the second conventional technique to always control the temperature within the allowable temperature range.
Japanese Unexamined Patent Application, First Publication, No. 4-326211 discloses a third conventional technique for suppressing beat generation in e wireless communication terminal. FIG. 26 is a diagram illustrating examples of variations of temperature and transmission power of tie conventional wireless communication terminal. When an output from a temperature detecting unit having a temperature sensor becomes beyond a predetermined lower reference value Tu, then a transmission time period is limited to terminate the transmission after a predetermined time has lapsed. If the temperature is further risen and becomes higher than a predetermined higher reference value TH, then the transmission is inhibited to suppress any further heat generation.
The third conventional technique suppresses the transmission power once after the temperature has risen over the threshold as upper limit of the allowable temperature range. Namely, it is difficult for the third conventional technique to always control the temperature within the allowable temperature range.
Japanese Unexamined Patent Application, First Publication, No-9-214363 discloses a fourth conventional technique for suppressing heat generation in the wireless communication terminal. FIG. 27 is a block diagram illustrating a typical example of the conventional internal configuration of the wireless communication terminal. FIG. 28 is a diagram illustrating examples of variations of temperature and transmission power of the conventional wireless communication terminal. A limited period of time is set based on the transmission output mode or the transmission power. When a continuous transmission time becomes beyond the limited time period, the transmission is discontinued in a predetermined period of time in order to prevent a further heat generation. Otherwise, the transmission is continued while reducing the transmission power in order to reduce the heat generation.
The fourth conventional technique does not measure the temperature of the terminal. When an ambient temperature is lower than the ordinary temperature, the transmission power can, in a case, be reduced unnecessarily. When the ambient temperature is higher than the ordinary temperature, reducing the transmission power can, in a case, be insufficient because it is difficult for the fourth conventional technique to determine whether or not the transmission power should be reduced largely as compared to the normal case at the ordinary temperature. Even if the transmission power has been reduced, it is difficult for the fourth conventional technique to detect the magnitude of the temperature drop. It is thus difficult for the fourth conventional technique to determine whether or not the magnitude of the temperature drop is appropriate.
The above-described first, second, third and fourth conventional techniques allow the temperature rising over the threshold as upper limit of the allowable temperature range during the transmission operation of the terminal.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved apparatus and/or method. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.